• ‘Prokaryotes’ are not a monopheyltic group
  • Kingdoms Bacteria & Archaea; each with unique traits
  • most species diverse groups on Earth

• Diversity of ways of making a living
  • sources of energy to make ATP
  • heterotrophs
  • autotrophs (photosynthesis)

• Co-evolution with the planet and other organisms
  • oxygen poor to oxygen rich world
  • extremeophiles (temperature, pH, salt,etc.)
  • prokaryotes are most abundant organisms on Earth!

• First TRACES of living organisms
  • Graphite carbon from Canadian rocks
  • Formed by ‘prokaryotes’
  • ~ 3.9 billion years ago!

• Cyanobacteria form stromatolites
  • undisputed fossils = 3.5 bya
  • western Australia
  • layers of calcium carbonate precipitated over bacterial colonies

• Unicellular (some colonies)

• Small
  • microscopic to poppy seed

• Many Shapes
  • spherical, rod, spiral

• 1/2 are motile (taxis)
  • use flagellum

• Asexual: daughter cells identical to parent
  • rapid reproduction
  • not sustainable!
  • bad for genetic diversity

• Mutations are rare but fast reproduction

• Gene transfer occurs:
  • transformation =
  • transduction =

• Cyanobacteria: first evidence ~2.7 bya
  • aka blue-green algae
  • aquatic and photosynthetic
  • use chlorophyll

• Photosynthesis evolved independently in distant groups
  • monophyletic or paraphyletic?
  • cyanobacteria are a monophyletic group

• Eukaryotes acquired photosynthesis by engulfing cyanobacteria!

• Prokaryotes let us breath (O₂)

• Bacteria and Archaea cycle nutrients
  • break down dead things

• A small % of Bacteria cause disease
  • Lyme’s disease

• Bacteria clean pollution
  • https://spinoff.nasa.gov/Spinoff2010/er_5.html